The SUNF code is the simplified version of UNF code and is based on the unified Hauser-Feshbach and exciton model. SUNF code has been developed for calculations of fast neutron data for structural materials with neutron energies below 20 Mev. Besides elastic scattering channel, the code may handle decay sequence up to (n,3n) reaction, including 14 reaction channels. The energy spectra can be obtained and the output form is in the ENDF/B-6 format, but in file 5 form. For the ENDF-B-6 output, the incident energies are divided into two types: only cross section calculation; and those including neutron energy spectra.
The incident energies of neutrons are from 1KeV to 20 MeV. There are two parameters in this code: incident neutron energies number "NEL"; and the number of discrete levels of residual nuclei for the first particle emissions "NLV". The users can set the values of NEL and NLV according to the storage size of the computer used. The number of discrete levels of residual nuclei for the multi-particle emissions is not greater than 20.
A code for automatic adjustment parameters of optical model is needed to determine the optimal optical potential parameters as the input of this code. If the direct scattering data and the direct reaction data are available from other codes, one can input the data so that the results will include the direct process effects.